Older women who spend too much time sitting are more likely to die at an earlier age than highly active women, a large, long-term study says.

Researchers analyzed data from 93,000 postmenopausal American women. They found that women who spent more than 11 hours a day sitting or otherwise being inactive had a 12 percent higher risk of premature death from all causes than those who were inactive for four hours or less per day, Health News wrote.

Women who were inactive also were 13 percent more likely to die of cardiovascular disease, 21 percent more likely to die of cancer and 27 percent more likely to die of coronary heart disease, according to the study.

The women were 50 to 79 years old at the start of the study and were followed for 12 or more years.

"The assumption has been that if you're fit and physically active, that will protect you, even if you spend a huge amount of time sitting each day," study leader Rebecca Seguin, an assistant professor of nutritional sciences at Cornell University, said in a university news release. "But in doing so, you are far less protected from negative health effects of being sedentary than you realize."

Seguin said women begin to lose muscle mass at age 35, and that loss accelerates with menopause. Although working out regularly, especially with weights, can help counteract that effect, it's also important for women to incorporate more everyday movement in their lives.

"In general, a use-it-or-lose-it philosophy applies," Seguin said. "We have a lot of modern conveniences and technologies that, while making us more efficient, also lead to decreased activity and diminished ability to do things. Women need to find ways to remain active."